When does common groundsel bloom in New York?

Most often in December. Across 240 dated, research-grade observations of Senecio vulgaris in New York, the flowering season runs roughly February to December.

Peak December In flower 240 Examined 325 State New York

Flowering 240 in flower of 325 examined

53%

80%

78%

72%

80%

81%

83%

86%

71%

61%

90%

Proportion of examined Senecio vulgaris in New York in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	16	30	53%	36% to 70%
Feb	20	25	80%	61% to 91%
Mar	28	36	78%	62% to 88%
Apr	63	88	72%	61% to 80%
May	24	30	80%	63% to 91%
Jun	13	16	81%	57% to 93%
Jul	5	6	83%	44% to 97%
Aug	6	7	86%	49% to 97%
Sep	6	7	86%	49% to 97%
Oct	10	14	71%	45% to 88%
Nov	22	36	61%	45% to 75%
Dec	27	30	90%	74% to 97%

Peak flowering in Dec. Each bar is the share of Senecio vulgaris in New York observations in which someone actually recorded the reproductive state and found the plant in flower, not the raw number of flowering records. That distinction matters: people observe plants far more in spring than in winter, so a bare count of flowering records partly measures when people go outside. Dividing by the number examined removes that. 240 of 325 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. This is still a global aggregate and not a forecast for your garden: the same species flowers on different dates in different hemispheres. Where a species has fewer than 30 flowering records we do not draw this chart at all. Computed from 10.15468/dl.wt38fd.

What this is, and what it is not

This is a record of when people in New York found Senecio vulgaris in flower, not a forecast. It is computed only from observations made in New York, so it is not the species’ global average dragged onto a map: the same plant flowers on different dates in different places, and that is the entire point of the page.

It will not tell you what your particular plant will do this year. Bloom time moves with the season, with altitude, and with the weather, and a warm February pulls everything forward. We publish the distribution and the sample size, and we refuse to draw a month that too few people examined.

The plant

Senecio vulgaris

common groundsel

Sourcesevery claim on this page

GBIF (iNaturalist Research-grade Observations). Dated flowering annotations in New York. Every record achieved iNaturalist quality grade Research, which is applied upstream at export. 10.15468/dl.wt38fd. Retrieved 2026-07-14.
World Flora Online Plant List. The accepted name. CC0. Retrieved 2026-07-12.